Ocatane requirement increase reducing fuel and lubricant compositions



United States Patent 3,145,203 OCTANE REQUIREMENT TNCREASE REDUCING FUELAND LUBRICANT COMPOSHTKONS Duncan W. Frew, Jan, Pleasant Hill, Calif,assignor t0 Shell Oil Company, New York, N.Y., a corporation of DelawareNo Drawing. Filed Nov. 20, 1961, Ser. No. 153,756

8 Claims. (Cl. 25249.9)

This invention relates to improved hydrocarbon fuels and motorlubricants containing a mixture of nitrogencontaining additives whichreduce or suppress deposit formation in internal combustion engines.More specifically, this invention discloses novel fuels and lubricatingoils having improved characteristics with respect to octane requirementreduction and spark plug cleanliness.

In recent years combustion chamber deposits have caused increasedproblems particularly with respect to octane requirement increase,surface ignition and spark plug life. Various gasoline additives,chiefly organic phosphorus compounds and boron compounds, have beenintroduced commercially to combat the latter two problems. However, thesearch for effective deposit modifiers and deposit removers to combatoctane requirement increase has not been as fruitful, and the formationof deposits on combustion chamber surfaces still poses a knotty problemto gasoline manufacturers. While these deposits also cause increasedengine wear, preignition knocking and spark plug fouling, one of themost deleterious effects is the increase in octane requirement at enginedeposit equilibrium. Moreover, the formation of deposits on variousother parts of an internal combustion engine, i.e., fuel and air intakesystem, presents additional problems affecting efllcient engineoperation. The forma tion of deposits in a carburetor, for example, cancause sticking of the automatic choke, fouling of the venturi,restriction of idle air flow around the throttle blades, and otherconditions which adversely affect engine operating efficiency.

Deposit formation is usually the result of a heat-induced polymerizationof various hydrocarbon constituents and/ or decomposition products ofthe gasoline fuel and the crank case lubricating oil. Thispolymerization reaction is coupled with incomplete combustion of thefuel/air mixture in the engine to produce a non-volatile gum,impregnated with carbon and other combustion residues of the gasoline,e.g., lead salts. These materials become hard and flint-like and adhereto the interior surfaces of a combustion chamber as an agglomeratedeposit. Initially, these deposits are present as a thin, varnish-likematerial which is soluble in organic solvents. However, on continuedoperation of the engine, the deposits accumulate'and become a thick,insoluble thermo-insulating layer with the hardest flint-like depositsformed at high operatcombustion chamber the octane requirement of theengine gradually rises until a deposit equilibrium level is reached.Generally, it takes on the order of 50 to 100 hours of operation for anoriginally clean engine to reach an equilibrium octane requirement. Thedifference between the clean engine octane requirement and theequilibrium oc tane rquirement is called the octane requirement increaseor increment, usually abbreviated ORI, and is a function of both thefuel and the lubricant. Generally, certain fuel and lubricantcharacteristics and engine-operation conditions determine the amount andcharacter of the combustion chamber deposits formed. Additives whicheither remove formed deposits or serve to prevent the deposition ofmaterials on the various areas of the combustion chamber are referred toas octane requirement reduction agents (abbreviated ORR).

, 3,i4b,23 Patented Aug. 25, 1964 Some materials have been proposed asdeposit modifiers or preventers. Boron compounds, metal chelates andvarious combustion catalysts, for example, have been proposed to removedeposits and clean combustion chamber surfaces. In general, thesematerials have not been too satisfactory. In fact, there is a long andunsuccessful history of attempts to develop a deposit removal orpreventative additive which could be directly incorporated in the fuelor lubricant for spark ignition engines. Only very limited success hasbeen achieved although numerous additives have been tried.

Essentially all commercially available motor gasolines contain additivesof various types. The most common of these are the tetraalkylleadantiknock compound such as tetraethyllead and tetramethyllead, which areadded in concentrations up to 4 cc. per U.S. gallon in motor gasolineand up to 6 cc. per U.S. gallon in aviation gasoline. Otherorgano-rnetallic antiknock additives which may be used are suchmaterials as cyclopentadienyl nickel nitrosyl, methylcyclopentadienylmanganese tricarbonyl, iron pentacarbonyl, tris(acetylacetonate) iron,nickel Z-ethyl salicylate, bis(n-butyl salicylaldimine) nickel, vanadiumacetylacetonate, ferrocenes and the like. However, because of the risein criticality of ignition control problems such as pro-ignition, wildping, and rumble or pounding,

in modern automotive engines, most gasolines today also contain certainignition control additives. The most effective of the ignition controladditives in use currently, and those with which the invention isconcerned, are compounds of phosphorus and, to a lesser extent,compounds of boron. Phosphorus compounds which are useful as ignitioncontrol additives in leaded gasolines containing halohydrocarbonscavengers are alkaryl phosphates or phosphites as in Yust et al., U.S.2,899,212, issued June 2, 1959; alicyclic phosphates as shown in Yust etal., U.S. 2,765,220, issued October 2, 1956; carbocyclic phosphoruscompounds containing a direct carbon-to-phosphorus bond as in Yust, etal., U. S. 2,828,195, issued March 25, 1958; esterified thiophosphatesand thiophosphites containing at least one alkaryl ester group as inYust et al., U.S. 2,843,465, issued July 15, 1958; tri-heterocyclicphosphates as in Yust et al., U.S. 2,841,480, issued July 1, 1958;tri(beta-haloaliphatic) phosphites and phosphates as in Kolka, U.S.2,866,808, issued December 30, 1950; dimethyl monophenyl phosphates asin Orloff et a1. U.S.

2,911,431, issued November 3, 1959; dimethyl mono-.

phenyl phosphates as in Orlolf et al., U.S. 2,870,186 issued January 20,1959; and alkyl phosphates and phosphites.

Among the boron compounds useful as additives for abnormal ignitioncontrol are oleophilic group-substituted heterocyclic compounds of boronand nitrogen as shown in Scott et al., U.S. 2,821,463, issued January28, 1958; cyclic esters of boric acid as in Garner, U.S. 2,940,839,issued June 14, 1960; alkyl boronic acids as in Darling, U.S. 2,710,251,issued June 7, 1955; and esters of alkane diols and borom'c acids as inDarling U.S. 2,710,252, is sued June 7, 1955.

Such ignition control additives do not generally reduce the amount ofcombustion chamber deposits but rather they modify the deposits in sucha manner as to reduce abnormal ignition phenomena, e.g., by lowering theelectrical or thermal conductivity of deposits. Furthermore, suchadditives do not significantly reduce the tendency of the octane numberrequirement of the engine to increase.

It is accordingly an object of the invention to provide.

improved internal combustion engine fuels and lubricating compositionshaving reduced tendencies to form combustion chamber deposits. It isalso an object of the invention to provide a fuel which will reduce thequantity of combustion chamber deposits which are laid down in engines.It is an object of the invention to provide an improved lubricating oilwhich will reduce a the quantity of combustion chamber deposits whichare laid down in engines. It is a further object of the invention toprovide a fuel composition which will have a reduced octane requirementat engine deposit equilibrium. A still further object of the inventionis to provide a new method of reducing the octane number requirement ofengines already containing substantial quantities of combustion chamberdeposits. Another object of the invention is to provide an ORR agentwith properties such that it Will perform effectively in an internalcombustion engine under varying conditions. Still other objects willbecome apparent in the description of the invention.

Accordingly, it has been found that when certain alkyl substituted2-oxazolidones are used as gasoline and lubricating oil additives ininternal combustion engines, a significant reduction in octanerequirement is produced. More particularly, the use of such ORR agentsin either the gasoline fuel or the crank case lubricating oil,substantially eliminates engine deposits or at least minimizes depositsto a point where they are no longer a material consideration in engineoperation. This outstanding advantage is obtained without deleteriouslyaffecting other necessary characteristics of the fuel or lubricatingoil, such as stability, performance ratings, and the like.

The improved hydrocarbon fuels and lubricating oils of the inventioncontain a mixture of from about 0.01% v. to about 5.0% v. of analkyl-substituted 2-oxazolidone having the structural formula:

These alkyl-substituted 2-oxazolidones are oiland gasoline-solublecompounds composed solely of carbon, nitrogen, oxygen, and hydrogenwherein R and R represent loW-molecular-Weight alkyl radicals containingfrom 1 to 4 carbons atoms and R can also be a hydrogen atom. The abovestructural formula will be referred to hereinafter as (I).

Specific examples of the ORR agents of the invention includeN-methyl-Z-oxazolidone, i.e.,

F CH2 0 0 CH; N-ethyl-2-oxazolidone, i.e.,

CH o CH: C=O

i CI'IZCHQ N-propyl-5-ethyl-2-oxazolidone, i.e.,

onaornjl l H CH 0:0 N

I CH CH CH Quite unexpectedly, it was discovered that the materials ofFormula I produce significant reductions in octane requirement andengine deposit (i.e., one Research Octane number and greater). Thisresult is particularly significant and unexpected when the materials ofFormula I are compared to related 2-oxazolidones wherein the nitrogenatom is not alkyl-substituted. For it has been discovered that the2-oxazolidones are not effective as ORR agents unless the nitrogen atomis substituted with an alkyl radical having from one to four carbonatoms. Further, it has been found that the unexpected ORR properties ofthe materials of Formula I are limited to nitrogen-substituted2-oxazolidones wherein the number 4 atom in the ring, that is the carbonatom adjacent to the nitrogen atom, contains only bydrogens. That is, ifthe number 4 carbon atom is substituted with anything other thanhydrogen, the resultant compound is ineffective as an ORR agent.

The mechanism by which the materials of Formula I function is notthoroughly understood; however, it has been determined that theeffective ORR agents of the invention are unexpectedly limited to the Nalkyl-substituted 2-oxazolidones of Formula I. Moreover, it is preferredthat the materials of Formula I contain 10 or less total carbon atoms toinsure optimum effectiveness.

In a further preferred embodiment of the invention the materials ofFormula I are used in gasoline motor fuel compositions containingphosphorus and boron surface ignition-control additives such asdisclosed in US. Patents, 2,889,212, 2,765,220, 2,828,195, 2,843,465,2,841,480, 2,866,808, 2,911,431, 2,870,186, 2,821,463, 2,940,839,2,710,251 and 2,710,252.

The ORR agents of this invention can be introduced into the combustionzone of the engine in various ways to accomplish a reduction in depositsand to prevent fur ther accumulation of engine deposits. Thus these ORRagents can be injected directly into the intake manifold intermittentlyor substantially continuously as desired. A preferred method is toincorporate the mixture into the fuel composition. For example, it canbe added separately to the fuel or blended with other gasolineadditives. Moreover, the additives can also be introduced into thecombustion chamber as a separate fuel charge during those periods ofengine operation at which the hardest deposits are more likely to form,thereby effecting economy in using the additive. Spark ignition enginefuels, jet engine fuels and also compression engine fuels can be treatedin this manner.

Another preferred method of introducing an ORR agent of the inventioninto the combustion chamber is as an additive to the crank caselubricating oil. Such a lubricating oil is effective in maintainingdeposits at a low level with the result that an engine lubricatedtherewith will show exceptionally clean cylinder head, combustion chainber, intake valve and piston crown and ring areas. Deposits on surfacescontacted by these lubricating oil containing additives, such as pistonskirts and cylinder walls, are markedly reduced.

The ORR agents of the invention are effective in motor fuels andlubricating oils in total concentrations as low as about 0.02% by volumebut total concentrations of about 0.05 to about 1.0% v. are normallyemployed. There is no critical upper limit of concentration but economicconsiderations dictate that the total concentration of the additive beless than about 5% V. in the fuel. In a preferred embodiment thematerials of Formula I are employed in concentration of about 0.5% v. Itis further understood that mixtures of various materials of Formula Ican be employed within the concentration limitations set forth above.

The fuel to which the additive is added is preferably a gasoline boilingin the range of about 30 F. to 450 F. and usually about 30 F. to about425 F., preferably consisting mainly of hydrocarbons. However, theadditives can also be added to diesel engine fuel comprisinghydrocarbons boiling in the range of about 400 F. to 750 F. and to jetengine fuels comprising hydrocarbons boiling in the range of about F. to600 F. The fuels used in this embodiment of the invention can contain inaddition to the compounds of Formula I any of the fuel additivescommonly used in the art such as organometallic antiknock agents, i.e.,tetraalkyllead, and other organo-metallic additives such as ironpentacarbonyl, methylcyclopentadienyl manganese tricarbonyl and halogenscavengers such as ethylene dibromide and dichloride. In addition to theabove additives, the fuel composition of the invention can andordinarily will contain other additives, for example, dyes, spark pluganti-foulants such as tricresyl phosphate, dimethyl xylyl phosphate anddiphenyl cresyl phosphate, combustion modifiers such as alkyl boronicacids and lower alkyl phosphates and phosphites, oxidation inhibitors,metal deactivators such as polymerized linoleic acids andN,C-disubstituted imidazolines and the like. The ORR agents of theinvention are effective in hydrocarbon fuels which do not containantiknock and other organo-metallic additives; however, in a preferredembodiment of the invention the ORR agents are used with hydrocarbonfuels containing organo-metallic antiknock additives, preferably atetraloWer-alkyl lead compound as tetraethyllead, tetramethyllead,methyl triethyl lead and the like.

The lubricating oils to which the ORR additives of the invention areadded are preferably mineral oils. They can be paraffin base, naphthenebase or mixed paraflinnaphthene base distillate or residual oils.Lubricating oils having an SUS viscosity at 100 F. between about 50 and1,000 may be used. These lubricating oils will usually contain otheradditives such as detergents and dispersants. A preferred lubricatingoil for use in the invention is a non-ash forming mineral oil within theSAE 30W range.

This invention also contemplates the combination of hydrocarbon fuelscontaining an ORR agent of Formula I used in conjunction with alubricating oil containing the same or a related ORR additive. In thismode of engine operation the ORR agent is added to the hydrocarbon fuelin a concentration of about 0.01 to 1% by volume and to the lubricatingoil in a concentration of about 0.05 to 1% by volume.

The following are examples of compositions suitable for use according tothe invention.

Example I Catalytic reformate 99.9 v. N-methyl-Z-oxazolidone 0.1% v.Phenyl discresyl phosphate 0.2 theory. Methylcyclopentadienyl manganesetricarbonyl 0.5 g. Mn/ gal.

Example II Catalytic reformate 98.75% v. Mixture of:

N-n-pr0pyl-2-0Xazolid0nc 1.0% v. N-isopropyl-2-oxazolidone 0.25% v.Cresyl diphenyl phosphate 0.4 theory.

Example 111 Straight run gasoline 80% v. Butene-isobutane motor gasolinealkylate 19.5 v. N-ethyl-S-methyl-Z-oxazolidone 0.5% v. Tricresylphosphate 0.3 theory. Example IV Platformate (containing 3 cc. tetramix/gal.) 99.0% v. N-butyl-Z-oxazolidone 1.0% v. Tricresyl phosphate 1.0theory. Example V A method of operating an internal combustion enginewherein a catalytic reformate gasoline containing 0.5% v.N-n-butyl-2-oxazolid0ne and 0.3 theory phosphorus as cresyl diphenylphosphate is used as a fuel; a mineral oil SAE l0W-30 at 99.5% v. havinga viscosity of 120 SSU at 100 F. and containing 0.25% v.N-ethyl-S-isobutyl-Z- oxazolidone is used as lubricating oil.

6 Example Vl Mineral lube oil having a viscosity of 320 SSU at C 99.9%V.

N-methyl-5-isobutyl-2-oxazolidone 0.1% v.

I claim as my invention:

1. An improved fuel composition for use in internal combustion enginesconsisting essentially of a stable gasoline boiling between about 30 F.and 425 F. containing an octane number-improving amount of anorganometallie primary antiknock agent, a minor amount of an ignitioncontrol additive selected from the group consisting of phosphorus andboron compounds and mixtures there of, and from about 0.01 to about 5.0%by weight of a gasoline-soluble, alkyl-substituted 2-oxazolidonecomposed solely of carbon, hydrogen, nitrogen and oxygen having thestructural formula wherein R and R are low-molecular-weight alkylradicals containing from 1 to 4 carbon atoms, and R can also be ahydrogen atom.

2. The composition of claim 1 which contains from 0.05 to 1.0% by weightof the alkyl-substituted 2-oxazolidone.

3. The composition of claim 1 in which the alkyl-substituted2-oxazolidone is N-ethyl-2-oxazolidone.

4. An improved lubricating oil composition for use in an internalcombustion engine having an SUS viscosity at 100 F. between about 50 and1000 and consisting essentially of a minor amount of an ignition controladditive selected from the group consisting of phosphorus and boroncompounds and mixtures thereof and from about 0.01% by weight to about5.0% by weight of an oil-soluble alkyl-substituted 2-oxazolidonecomposed solely of carbon, hydrogen nitrogen and oxygen, and having thestructural formula References Cited in the fil: of this patent UNITEDSTATES PATENTS Orelup et al. Nov. 20, 1928 Steele et a1 Apr. 12, 1960

1. AN IMPROVED FUEL COMPOSITION FOR USE IN INTERNAL COMBUSTION ENGINESCONSISTING ESSENTIALLY OF A STABLE GASOLINE BOILING BETWEEN ABOUT 30*F.AND 425*F. CONTAINING AN OCTANE NUMBER-IMPROVING AMOUNT OF ANORGANOMETALLIC PRIMARY ANTIKNOCK AGENT, A MINOR AMOUNT OF AN IGNITIONCONTROL ADDITIVE SELECTED FROM THE GROUP CONSISTING OF PHOSPHORUS ANDBORON COMPOUNDS AND MIXTURES THEREOF, AND FROM ABOUT 0.01 TO ABOUT 5.0%BY WEIGHT OF A GASOLINE-SOLUBLE, ALKYL-SUBSTITUTED 2-OXAZOLIDONECOMPOSED SOLELY OF CARBON, HYDROGEN, NITROGEN AND OXYGEN HAVING THESTRUCTURAL FORMULA